Silicone based aqueous dispersions crosslinkable into elastomeric sealants and coatings are known in the art. They generally comprise an oil in water emulsion of a polyorganosiloxane with hydroxy endgroups, a crosslinking agent, a non-siliceous inorganic filler and a curing catalyst. In particular, a great deal of effort has been directed to emulsions of standard .alpha.,.omega.-dihydroxypolydimethylsiloxane fluids in combination with many different crosslinkers as a basis for producing silicone latex sealants. The crosslinkers have included alkoxysilanes (U.S. Pat. No. 4,100,129), colloidal silica (U.S. Pat. No. 4,221,688), sodium silicate (U.S. Pat. No. 4,224,849), silsesquioxanes (U.S. Pat. No. 3,355,406), siliconates (EP 266 729), and reactive resins (U.S. Pat. No. 4,554,187). More recently the use of a disiloxane curative has been disclosed (WO 98/13410, Rhone Poulenc). Unfortunately, these emulsions have suffered from poor shelf stability, poor adhesion and poor physical properties.
Combinations of silicone emulsions and acrylic emulsions have been recently suggested to address some of these issues (U.S. Pat. No. 5,360,851 and EP 246 537, Rhone Poulenc). Similarly, U.S. Pat. No. 5,621,038 to Chen et al. discloses the modification of dispersion polymers with vinylsilanes containing hindered alkoxy groups. However, it does not mention silicone polymers modified with these vinyl silanes. U.S. Pat. No. 5,686,523 discloses the mixture of a dispersion polymer modified with a silyl group and an additional silane additive in the form of an alkoxysilane with hindered alkoxy groups.
U.S. Pat. No. 5,714,532, incorporated herein by reference, describes a series of alkoxysilanes which can be formulated into stable emulsions for waterborne coating or sealant formulations as crosslinkers or adhesion promoters.
Co-pending U.S. application Ser. No. 09/149,337, filed Sep. 8, 1998, incorporated herein in its entirety by reference extends the use of hindered silanes as additives to waterborne acrylic sealants. Increases in adhesion, shelf life and sealant physical properties are noted. In this technology the silanes are used as additives to a resin system or are incorporated into the resin during resin synthesis.